A small example of quick sort

function quickSort($array)
{
if( !isset( $array[1] ) ) return $array;
$mid = $array[0]; //Get a keyword for splitting , usually the first element
$leftArray = array();
$rightArray = array();
foreach( $array as $v )
{
if($v > $mid)
$rightArray[] = $ v; //Put the number larger than $mid into an array
                                                                                                                                                                                                                                              can be put the numbers larger than $mid into an array.
}
$leftArray = quickSort($leftArray); //Split the smaller array again
$leftArray[] = $mid;
$rightArray = quickSort($rightArray); //Split the larger array again
return array_merge($leftArray,$rightArray); //Combine the two results
}
print_r( quickSort( array( '6' ,'5','3','7','9' ) ) );
The above introduces a small example of quick sorting, including aspects of content. I hope it will be helpful to friends who are interested in PHP tutorials.